As high-voltage and high-energy density batteries, for example, Li ion batteries are known. The Li ion battery is a cation-based battery utilizing the reaction between a Li ion and a cathode active material, and the reaction between a Li ion and an anode active material. Meanwhile, as anion-based batteries, fluoride ion batteries utilizing the reaction of a fluoride ion (a fluoride anion) are known.
For example, Patent Literature 1 discloses the use of Cu as the cathode active material of a fluoride ion battery. As described in Patent Literature 1, metals (Me) such as Cu are known to exhibit a function as the active material of a fluoride ion battery by a fluorination-defluorination reaction (MeFx+xe−←→Me+xF−). Also, Patent Literature 2 discloses a fluoride ion battery utilizing PbSnF4 as a solid electrolyte.